Metadata may be used to guide the display of image data. Metadata may, for example, convey a wide range of information such as locations and types of light sources depicted in an image; protected colors that should not be altered; statistical information regarding an image that may be of use in decoding and/or displaying a high quality version of the image; information regarding how image data has been encoded; and so on.
Metadata may be transmitted between a source and a display via any suitable data communication channel however it can be undesirable to have to set up separate communication channels for image data and related metadata. The inventors have recognized that there is a need for ways to provide metadata or other information in a format that facilitates delivery of the metadata together with image data. There is a particular need for such formats which allow image data packaged for delivery together with metadata or other information to be carried by a standard image data transmission fabric.